I suggest an attorney as you clearly don't understand anything of what I wrote. Last time:
Would that have been enough to ensure that it is left to me (even if my sister didn't fight for it)?
A will will go through probate. A person can fight a will for the same reasons they could fight title transfer.
Can I just see a lawyer and file a quitclaim deed to get my name off the deed now, instead of what you suggested?
That would be giving a gift of the property to the person you quitclaimed to.
The only reason I put my name on the list was because all of the people in my Mom's condo did this and I guess they didn't know about all you're telling me. Everyone was under the impression that having their child as the co-owner was the best route to go.
Looks like everybody was wrong.
After reading the step up information, it looks like I may be hit with penalties that would cancel out any profits from selling the apartment, that I can't afford.
There are no penalties and it is not possible to cancel out any profit from the sale.
Would the step-up only apply if I actually sell the condo? What if I just live there and keep it forever?
A step-up in basis is only relevant for depreciation (if you are going to depreciate the property) or on the property's sale. It affects the BASIS.
For example (Not correct, just as illustration. I am not going to get into the issues related to the amount of the property which was gifted as that would be like Rocket Surgery as to this.):
Mom's basis: $100
Property value at death: $200
Because it was a gift, you take mom's basis on the property. If you inherited it, you would get as your basis the value at death. Now, say you sold the property for $300. The amount you sell the property for minus the basis is your gain. It is a capital gain and you would pay taxes on that amount. In our example, the amount you would pay taxes on:
As a gift: $300 - $100= $200 capital gain.
As inherited: $300 - $200= $100 capital gain.